Davost, thank you very much for your post. I am finally getting somwhere.

Now I also manage to gain access to the V4L2_CID_FOCUS_ABSOLUTE value and can manually control the focus of the camera.

The aim of my application is to only access the value of V4L2_CID_FOCUS_ABSOLUTE that is set by the auto focusing feature. If I use native camera app to focus on different objects, V4L2_CID_FOCUS_ABSOLUTE parameter changes.

Now I would like to write my own application that auto focuses on an object like the native camera. I managed to open a GStreamer pipeline, but can not activate auto focusing option.

The Question:
Does the native camera app implement the auto focusing algorithms, or, there is a library or hardware option that enables auto focus functionality?

Bellow are all the values that are supported by the N900 main camera.

ID: Control Name: Value
9963776: Brightness:0
9963777: Contrast:16
9963793: Exposure time [us]:33000
9963795: Gain [0.1 EV]:28
9963807: Color Effects:0
10094858: Focus, Absolute:105
10094862: Flash timeout [us]:1000
10094863: Flash intensity:12
10094864: Torch intensity:0
10094865: Indicator intensity:0
10096766: Test pattern mode:0
10096815: Focus ramping time [us]:3200
10096816: Focus ramping mode:2
10096881: Short-circuit fault:0
10096882: Overtemperature fault:0
10096883: Timeout fault:0
10096884: Overvoltage fault:0
10160385: Frame width:1593
10160386: Frame height:504
10160387: Visible width:684
10160388: Visible height:492
10160389: Pixel clock [Hz]:96533333
10160390: Sensitivity:65536